Collagen is a structural protein found naturally in high amounts in poultry skin and bones. Gelatin is obtained by a partial hydrolysis of collagen under controlled conditions. It is a pure protein with many functional and technological properties such as gelation, thickening, film-forming and emulsification. Besides skin and bones, mechanically deboned meat (MDM) residues are considered good sources of collagen as well.
A Turkish study published in Akademik Gida aimed to extract collagen and gelatin from poultry skin and MDM residues of neck, shinbone, breastbone, wingtip, shanks, upper/lower backbone and their mixture through pre-treatment (using with dilute alkali and acid), demineralization, degreasing and thermal extraction processes, and evaluate their properties comparatively. Based on Kjeldahl analysis, the protein content of poultry skin was about 15% and that of the MDM residues varied between 15-21% before the extraction process. The SDS-PAGE profiles of the extracted collagen in skin and MDM residues comprised gamma, beta, alpha, and sub-alpha chain protein units. Collagen solution of the upper backbone and mixed MDM residues had the highest protein content with 11.98 mg/mL and 11.33 mg/mL, respectively. The extraction yield of collagen and gelatin significantly differred (p<0.05) within the range between 1.32 and 2.16%, and 1.03 and 1.89%, respectively. The viscosity of collagen/gelatin solutions decreased with an increase in shear rate and gelatin obtained from mix MDM residues indicated higher viscosity than that of skin.
Of this study showed successful recovery of collagen and gelatin from poultry processing by-products and residues, which could contribute to the production of high value-added alternative sources for various applications.
